dyno, 1st run 155hp, remaining 4 runs 172hp. wtf?
 

I just dyno'd the BRZ (2017 PP), the first run was significantly low on power up top relative to the rest:
131.5 lb-ft @ 3250, 154.5hp @ 6600
Torque rose linearly from 122 lb-ft @ 5000 to 127 at 6150, then began falling off.
92 lb-ft and 130hp @ 7400

The remaining four runs were all practially identical:
134 lb-ft @ 3300 and 6750, 172hp @ 6800
Torque rising linearly from 126 lb-ft @ 5000 to 134 @ 6750
106 lb-ft and 150hp @ 7400

A/F was a remarkably constant 13.0 - 13.1 for all runs from 2700rpm to the rev limiter.

If I had to guess I'd say the VVT wasn't working on the first run, is there anything that could prevent it from engaging?
The car sat for a while before the first run, but it wasn't too too far from normal operating temperature, nowhere near stone-cold.

Anyway, pretty pleased with the last four runs but would like to figure out why the first run was so different.

I'd guess that oil wasn't up to temp on the first run. I know that on my car even when water temp starts to get into the 180-190 range the oil temp is significantly cooler and doesn't hit 190 for quite a while.

Oh, I'd suggest you just average the results from the last runs …… and call the first run an "outlier".


:)


humfrz

Your 2017+ US cars have a strange logic.. With wot Closed loop and "power" afr and other stuff...
That s also why Openflash went with old logic for v4 tunes

Vvt takes long to activate if oil is quite cold, specially after reflash or dtc reset

Is the car stock?

Stock ECU tune?

Engine, intake, exhaust, tune all totally stock.
Oil temp was down for 1st run, coolant closer to normal.
So if vvt is sensitive to oil temp that must be it.

For the other runs, I've never seen multiple dyno runs so close together, and A/V as well. Nice...

Which octane gas used?

A/c was on for the first run.

100% because oil not up to operating temperature.

I used to have a Renault that would not allow me to rev it to the 7250 RPM limit until the oil was up to temp. Once water was up to temp you'd need to drive it around for another 5 mins before it'd let you rev it past 6500.

Probably a similar thing to do with the vvt not engaging fully until oil temp is to the correct level.

Sent from my RNE-L02 using Tapatalk

Stock tune also has IAM set to 0.7. So the first pull wouldn’t have full timing.

Could be many causes; without a log I wouldn't be able to guess, but the car is otherwise totally happy!

Yeah, totally fine. If oil has to be at full normal operating temperature for VVT to be in effect, then that's it for sure. It probably sat for over an hour before we ran it. Car seems happy enough :)

it doesn t need to be full normal temperature, it just must be warmed for about 3 minutes or less
i think with vvt off you could do less than 155hp


i think ermax is right, was easy actually, it s just the AM at 0.7 at start that need some heavy pulls to go up

Does the stock tune reset to .7 on each startup? I haven't been on one for a while and never checked.